Various injection devices have been described, which comprise energy storing means, such as a spring member, in which energy is stored during dose setting. Subsequently, during injection of a previously set dose, energy stored in the energy storing means is released and used for driving an amount of drug corresponding to the previously set dose out of the injection device.
Examples of such injection devices are shown in WO 2006/045528 and in WO 2006/045529. The injection devices disclosed in WO 2006/045528 and in WO 2006/034429 both comprise mechanical means, in the form of a dose indicator barrel, for detecting and displaying the amount of a set dose. During injection, the dose indicator barrel returns to its initial position, and it is thereby also capable of indicating the amount of an injected dose.
In some cases it may be desirable to store and/or log data relating to the injections performed using the injection device, e.g. in order to be able to compare such data. However, it is undesirable if this results in an increased size of the injection device.
Furthermore, in some cases it is desirable to provide an electronic display at an exterior part of the housing of the injection device for displaying various relevant parameters, such as set dose, injected dose, time lapsed since last dose was injected, kind of medicament contained in the device, etc. At the same time, it is desirable to be able to monitor relevant parts of the injection device, in particular to monitor movements of such relevant parts, in order to obtain desired information to be displayed at the display.